The invention relates to an inner conductor of a co-axial gyrotron with axial corrugations distributed uniformly around the periphery. The metallic electrically conductive inner conductor begins at the front of the cathode and extends beyond the whole resonator space of the gyrotron.
The corrugations can be considered to be an area with two co-axial inner conductors of different diameters. They serve for the mode selection.
Corrugations at the inner conductor with constant depth are known in the art [1]. Such a structure with constant depth permits in a limited way, to manipulate the course of particular mode functions in axial direction.
Based on this state of the art, it is the object of the present invention to improve the mode selection in the resonator of a co-axial gyrotron in such a way that a technical utilization of a gyrotron with such a corrugated inner conductor is technically attractive.
In an inner conductor of a coaxial gyrotron, which inner conductor is disposed on the cathode of the gyrotron and includes an entrance funnel, a center part and an exit funnel, axial corrugations are formed in the conductor by axial grooves formed into its wall such that they begin at the end of the entrance funnel and have in the center part an increasing depths up to the exit funnel in which the depth again becomes steadily smaller, the corrugations being evenly distributed about the inner circumference of the inner conductor.
Important is that the corrugations become monotonously deeper toward the center part of the resonator starting from the area of the entrance funnel of the center part of the resonator up to the end of the center part of the resonator. From here on the corrugations in the area of the outlet funnel have a uniformly decreasing depth. xe2x80x9cUniformlyxe2x80x9d means that the corrugations may start out smooth may remain smooth and end smooth.
The deepening corrugations at the inner conductor in the area of the inlet funnel and the center area permit to influence the course of the individual value functions of the modes in axial direction additionally in a selective manner to increase the start-up currents of undesirable modes, to increase the operating field of the operating mode and also to improve the efficiency of the gyrotron. With this measure, the small losses in the inner conductor in axial direction are homogenized and their cooling is facilitated thereby.
The invention will be described below in greater detail on the basis of the accompanying drawings.